Shell grommet



NOV. 19, 1940. H. HUSTED I 2,222,456

SHELL GROMMET Filed Aug. 20, 1940 2 Sheets-Sheet l ENTOR HARR HUSTED BY Patented Nov. 19, 1940 PATENT OFFICE 1 SHELL GROMMET Harry A.

Standard Products Company,

Busted, Detroit, Mich., assignor to Port Clinton,

Ohio, a corporation of Ohio Application August 20, 1940, Serial No. 353,320

12 Claims. (Cl. 102-1) The invention relates to a rifiing band protector, sometimes known as a grommet. It is particularly useful in connection with the handling of-ordnance shells of conventional cylindro-con- 5 ical contour which are handled or stacked in a manner involving continued or occasional undesired contact with each other or with surrounding objects. Although described in detail here-- in with reference to shells of this nature, it is immediately apparent that any article of generally cylindrical contour which must be handled, stacked, or transported, and which should be protected from accidental shock or impact, may be used in connection with my device in the manner to be described.

As is well known to those skilled in this particular art, most projectiles are fired from rifled gun barrels. The service life of a gun depends on the condition of the rifiing grooves therein.

m The shells are usually provided with a band of soft metal, such as copper, superimposed on the shells exterior periphery at a suitable point, which soft metal band bears against and within the grooves as the shell is fired. The use of a ,5 soft metal band to seat in, and protect, the gun rifling is well known to ordnance experts.

When projectiles are being handled, piled, or shipped after final assembly, they may be subjected to unavoidable rough handling, and some- 30 times, when in actual use in the field, they must be transported for considerable distances over rough roads or irregular terrain, by truck or in any other possible manner. The effect of stacking, rough handling, or jolting becomes immedi- 35 ately apparent upon the soft metal band which,

obviously, must protrude circumferentially beyond the balance of the cylindrical periphery of the shell. The accuracy and efliciency of gunfire depends on the maintenance of accurate di- 40 mensions in the rifling band.

It is an important object of my invention, therefore, to provide an improved method and means for protecting the rlfling band of shells while they are being handled, stacked, or shipped or 45 in any way dealt with prior to loading.

It is a further object to provide improved means for preventing or cushioning surface contact between cylindrical objects which frequently are located in juxtaposition, or in danger of con- 50 tact with each other.

It is a further object to provide such improved protective means which requires no auxiliary fastening devices, and no specialtools for installation, since it can readily be mounted, or removed, manually.

Further objects and attendant advantages will be apparent on consideration of the following description and the drawings attached herewith illustrating a preferred embodiment.

Fig. 1 shows a metallic blank to be used as a backbone member for one embodiment of my improved device.

Fig. 2 shows the backbone member in a further phase of manufacture, in which beads are formed upon its longitudinal edges, and spring wires inserted therein.

Fig. 3 shows in elevation, and viewed edgewise,

a protective grommet in normal unstrained position, before mounting.

Fig. 4 shows a projectile, partly in section, carrying a rifiing band with a protective grommet or collar placed thereon.

Fig. 5 is a section on the line 5'-5 of Fig. 4.

Fig. 6 is an enlarged view of a portion of Fig. 4.

Figs. I to 16 inclusive show nine standard designs of rifling bands at present in use on projectiles for the military and naval forces of the United States. The drawings illustrate the bands in section, with a grommet in place in each instance, the greater portion of the projectile .being broken away. I

In preferred form the grommet comprises a split ring or annulus which normally, that is tosay when not in final seat upon a shell, is char- 3o acterized by a contour involving a certain amount of overlap at the ends thereof. This overlap is the result of a manufacturing step in which the material, before or after cutting to final length, is formed to a somewhat smaller diameter than it is calculated to eventually assume. Upon release from the forming means, it springs to the overlapped contour shown, for example, in Fig.

3. If made in the manner hereinafter described the ends may be grasped and manually drawn apart sumciently to fit it over the rifling band on a shell. The length of the piece of stock should be precalculated so that when finally seated, as shown in Figs. 4 and 5, the ends closely approach each other. They might actually abut against each other provided the spring grip'of the collar upon the rifling band is not disturbed thereby.

In the manufacture of one form of my improved protective device, I first provide a continuous metallic backbone strip l0, having serrated longi- 5o tudinal edges II and a central zone I! which is preferably perforated throughout its length, as shown at 13 in Figs. 1 and 2. The purpose of the said perforations it to provide a key or anchoring effect in a coating as will soon appear;

ductile enough, to withstand the strains of service and the corrosive effect of weathering, etc. I prefer to use a cold rolled electro-galvanized steel but a variety of suitable metals and alloys can be suggested by those skilled in the metallurgical arts.

The outer extremities of serrations H are next turned inwardly over and around two longitudinally extending wires or rods I4 preferably of spring steel, so as to form an enlarged bead along each edge of the backbone member, as best seen in Fig. 6. In clipping each head about the wire, care should be taken to leave a small amount of play therebetween to permit relative motion during flexing. As a material for the wire I prefer an oil tempered, spring wire of manganese steel, but here also a variety of alloys of substantial equivalency are available. This operation may be performed in any suitable manner, for instance by running the strip through a succession of pairs of coacting rolls whose cooperating surfaces are concaved, or otherwise disposed to perform the above described operation progressively or in a sequence of steps, as is well understood in the art.

A coating or jacket of soft material I5, for instance rubber, or rubber-like material, plastic, textiles, synthetic resins, pulps, or in general any one of a number of organic materials, is now applied to the backbone member, preferably by a familiar extrusion process. In the perforated form of backbone here illustrated the plastic material flows through the perforations I3 and forms an interlocked or anchored bond. As shown in Fig. 6 the metal is completely enclosed by the coating.

A facing sheath [6 of nonadhesive material such as cotton fabric is placed upon the coated strip, completely shielding the inner face and both edges and running over a portion of the other face. If applied while the coating is still tacky the fabric will permanently bond thereto. The bond between the coating material and the fabric may be improved if the fabric is coated with latex on the side contiguous to the coating material. The purpose of the fabric facing will hereinafter appear. Briefly, it prevents adhesion between the coating and its eventual seat.

If, for example, my invention is to be used to protect the rifiing band on a projectile of about 8 inches in diameter the completed composite strip comprising the backbone member ID, the coating I 5, and the fabric facing strip IE, will eventually be cut into lengths of approximately 25 inches, representing a length suflicient to surround the periphery of the rifling band. These lengths may then be bent with a permanent set around a cylindrical die of a diameter substantially less than 8 inches by a suitable mechanical device, or otherwise be so formed, so that when released they expand slightly towards a contour such as shown in Fig. 3, but with a diameter which still is less than 8 inches. Alternately the endless composite strip, before cutting to length, may be wound in a close spiral by passage between rollers or over a cylindrical die of somewhat reduced diameter and thereafter cut to suitable lengths or the precut lengths may be so rolled individually. Either method, or others which may suggest themselves, will apply suiflcient stress to induce a tendency to maintain a contour as seen in Fig. 3 which is elastically deformable, to a considerable degree, radially.

The actual sequence of steps involved in the production of a commercial embodiment of my invention is as follows: Thebacking strip of ferrous metal is first perforated and its edges serrated to a predetermined design. The spring steel wire is then placed along each edge and the edges rolled inwardly over the wire so as to retain the wire in a bead thereby formed. Preferably the clamping grip of the strip serrations on the wire should be loose enough to allow a slight amount of play, since the completed article will eventually be subjected to alternating flex- 15 ures, as will appear. The strip material is now covered with a rubber-like organic composition and a facing strip of some nonadhesive fabric, for instance cotton fabric, is then applied to the organic material, The coating may now be cured in place, for instance by heating, as is well understood in the art. The strip, thus coated, is finally cut to proper lengths and formed to the previously described overlapping annulus.

In Fig. 4, numeral l1 indicates a shell body carrying a rifling band l8 of some relatively soft metal such as copper or a copper alloy. 811- perimposed upon and surrounding the exposed portion of said rifling band is my novel protecting collar I9.

In the drawings the collar has been snapped into seating engagement around the projecting portion of the rifling band. The fabric facing material on the inner periphery of the collar prevents contact of the coating material with the soft metal band. Such contact would induce adhesion between rubber and metal and also encourage corrosion, especially since, in the present instance, the tendency is heightened by the substantial spring pressure of the split annulus. As seen in Fig. 6, the design of collar forming a preferred embodiment of my invention fits snugly around the exposed portion of the rifling band. The enlarged bead portions along the longitudinal edges of the collar are turned substantially radially inwardly so as to form ribs orflanges 2| which bear simultaneously against the side walls of the rifling band and protect its edges 22. Such collisions as are usually encountered are borne, primarily, by the projecting ribs 20. The coating is sufllciently resilient to cushion any ordinary impact. An additional feature of these ribs is that they tend to prevent shifting of a load in shipment, or in storage when stacked,

It is apparent, from the above description, that in the preferred form of my invention the enlarged beads formed along the edges of the protective collar serve a double purpose. They carry therewithin the resilient element, namely the spring wires within the tubular serrations of the backbone strip, above described, and by reason of the fact that they protrude inwardly of the surface level of the main body portion of the composite strip they show, in section, a channeled contour which slips radially inwardly over the annular projection of, the riding band, as seen for instance in Fig. 6.

Figs, 7 to 16 inclusive illustrate the adaptation of my invention to a series of standard rifling bands 23, now used on projectiles by the military or naval forces of the'United States. In each illustration I have shown, in section, a design. of grommet 24, which may be used, although obviously changes in contour and other characteristics may be made to suit the circumstances of manufacture and use in particular instances. Al-

though my preferred design of grommet involves an enlarged positioning head at both edges of the protective annulus, I may substitute for either or both of these edge beads an interior contour of the grommet face which includes one or more beads, projections, or depressions inwardly spaced from the longitudinal edges. The metallic strip member may be channeled, dished, or otherwise formed to generally conform to and support the external contour of the grommet.

Suitable strip metal and spring steel wire for a purpose such as hereinabove described are readily obtainable from manufacturers. The width of the backing strip is to some extent determined by the dimensions of the rifiing band to be protected. Its thickness may be varied within limits which a few trials will rapidly determine. A strip .008" in thickness has been found useful in one application. The completed annulus should be responsive to a simple test involving expanding it radially for a distance sufficient to permit clearance for the fingers while manually placing it in position, yet under such conditions it must, upon release, immediately return to its normal overlapping condition, unless it is seated upon a rifiing band, It will be apparent to those skilled in the metallurgical arts that these attributes are a function of the width and thickness of the metal strip, and the spring-like characteristics of the strip and/or wire. Instead of providing a steel strip of relatively malleable stock, reinforced by spring steel wires, I may dispense with the wires and use strip stock of spring steel.

It is further evident that my invention may be modified to some extent from the embodiments so far described, while still retaining to a large degree the advantages outlined above. I may, for instance, dispense with the steel backing strip and use a grommet with one or more resilient wires or cables. covered with suitable material such as rubber, or synthetic rubber for example. Individual grommets may be made for the conventional peripheral grooves on the rifiing band by coating a resilient wire, or a cable built up from a plurality ofresilient wires, with rubberlike material as hereinbefore described, to which may be added, if desired, a fabric facing. Such a construction is seen in Fig. 16, where I show a cable 25 coated with synthetic material 26, and seatedin a groove 21 in a rifiing band 23. The grommet in this case also is a split annulus.

Fig. 15 illustrates a further embodiment of my invention wherein satisfactory protection is achieved by means of a rubber or synthetic rubber grommet 28 having two circumferential edge beads 29, each containing therein a resilient wire or, as shown, a cable member 30. Obviously the number of wires or cable-like members used in such a grommet may vary and may, if desired, correspond with intermediate depressions or variations in the surface contour of the rifiing band. A resilient member of any of the types shown herein may be formed by a conventional extrusion process whereby the rubber-like material is extruded over the strip, wire or cable members. I Wherever in the appended claims I speak of the reinforcing or resilient member as a wire, I wish it understood that the term comprehends either a single wire or a plurality of associated wires commonly termed a cable. The terms mentioned have been used interchangeably in the specification, but for brevity I use the term e in the claims.

Although described in connection with the protection of the rifiing band of a projectile, it will be obvious that the invention could be utilized in the protection of cylindrical objects other than projectiles. My device-and manner .of applying the same, in any useful adaptation thereof, are comprehended within the-scope of the claims appended herewith, it being understood that the terminology or phraseology herein employed is for the purpose of description and not of limitation.

What I claim is: I

1. A projectile rifiing band protector. .comprising a split ring of spring characteristics similar to that of spring steel and of a length approximating. the circumference of the rifiing band for which it is intended, soft and resilient material on the face of the ring adjacent the rifiing band, said ring assuming a normal shape, when not in place on said rifiing band, approximating a circle of less diameter than that of said rifiing band.

2. A projectile rifiing band protector, comprising a split ring of spring characteristics similar to that of spring steel and of a length approin'm-ating the circumference of the rifiing band for which it is intended, relatively soft and resilient material on a longitudinal face of said ring, said ring assuming a normal shape, when not in place on said rifiing band, approximating a circle of less diameter than that of said rifiing band.

3. A projectile rifiing band protector, 'comprising a split ring of spring characteristics similar to that of spring steel and of a length approximating the circumference of the rifiing band for which it is intended, relatively soft and resilient material on the inner and outer faces of said ring, said ring assuming anormal shape, when not in place on said rifiing band, approximating a circle of less diameter than that of said rifiing band.

4. A projectile rifling band protector, com prising a split ring of spring characteristics similar to that of spring steel and of a length approximating the circumference of the projectile rifiing band for which it is intended, said ring including relatively soft and resilient material and a facing material for contact with the rifiing band, said ring assuming a normal shape, when not in place on said rifiing band, approximating a circle of less diameter than that of said rifiing band.

5. A projectile rifiing band protector, comprising a core of, material having spring characteristics similar to that of spring steel and of a length approximating the circumference of the projectile rifiing band for which it is intended, relatively soft and resilient material surrounding said core, and facing material on the inner face of said protector, said protector assuming a normal shape, when not in place on said rifiing-band,approximating a circle of less diameter than that of said rifiing band, with the ends overlapping each other.

normal shape, by reason of said spring-like part, when not in place on said rifling band, approximating a circle of less diameter than that of said rifling band, 4 I A '7. A projectile rifling band'protector in the form of a split ring, said ring having two parts, one of which has spring characteristics similar to that of spring steel and which with respect to said other part is slidable circumferentially, said ring being of a length approximating the circumference of the projectile rifling band for which it is intended and having relatively soft and resilient material on a longitudinal face thereof, and said ring assuming a normal shape, by reason of said spring-like part, when not in place on said rifiing band, approximating a circle of less diameter than that of said rifling band.

8. A projectile rifiing band protector, comprising a sheet metal member in the form of a split ring of a length approximating the circum ference of the projectile rifling band for which it is intended, said sheet metal member having hollow beads along its longitudinal edges, a spring member slidably carried within each of said beads and causing the sheet metal member to assume a normal shape, when not in place on said rifling band, approximating a circle of less diameter than that of said rifling band, with the ends overlapping each other, and relatively soft and resilient material on a longitudinal face of said sheet metal member.

9. A projectile rifling band protector as in claim 8, said protector being of a width such that said beads engage'exposed opposite edges of said rifling band. a

10. A projectile rifiing band protector, comprising a split ring of spring characteristics similar to that of spring steel and of a length approximating the circumference of the projectile rifling band for which it is intended, said ring having an inwardlyprojecting portion of relatively soft and resilient material for seating engagement on said rifling band, said ring assuming a normal shape, when not in place on said rifii'ng band, approximating a circle of less diameter than that of said rifling band, with the ends overlapping each other.

11. A projectile rifling band protector, comprising a split ring of spring characteristics similar to that of spring steel and of a length approximating the circumference of the projectile rifiing band for which it is intended, said ring having a portion projecting radially inwardly for seating engagement in a depression of said rifling band, said ring assuming a normal shape, when not in place on said rifling band, approximating a circle of less diameter than that of said rifling band, with the ends overlapping each other. v

-l'2. A projectile rifling band protector, comprising a sheet metal member having hollow beads along its longitudinal edges and said beads being interrupted to enable said sheet metal member to assume a split ring-like form, a springwire slidably carried within each of said beads and causing said sheet metal member to assume a normal shape, when not in place on said rifling I band, approximating a circle of less diameter than that of said rifling band, relatively soft material surrounding said sheet metal member and a facing of nonadhesive material on the inner face of the protector.

HARRY A. HUSTE). 

